Exhaust gases emitted by internal combustion systems utilizing hydrocarbon fuels, such as hydrocarbon gases, gasoline, or diesel fuel, can cause serious pollution of the atmosphere. Among the many pollutants in these exhaust gases are hydrocarbons and oxygen-containing compounds, the latter including nitrogen oxides (NOx) and carbon monoxide (CO). The automotive industry has, for many years, attempted to reduce the quantities of pollutants from automobile engine systems, the first automobiles equipped with catalytic converters having been introduced in the mid 1970's. Cordierite substrates, typically in the form of a honeycomb body, have long been preferred for use as substrates to support catalytically-active components for catalytic converters on automobiles.
Aluminum titanate (AT) ceramics have emerged as an excellent candidate for high-temperature applications. To achieve the desired porosity in such aluminum titanate materials, graphite pore formers have been added to the inorganic batch materials.